A polar bear eats a pumpkin at the Detroit Zoo in Royal Oak, MI, Wednesday, October 24, 2012. The polar bears, along with snow monkeys, gorillas, rhinos, zebras, bison, wolverines, and anteaters, received treats as part of the annual Halloween-themed enrichment program at the zoo.

The San Diego Zoo’s 6-month-old male cub jaguar, Tikal, rolls a jack-o-lantern around his exhibit at the San Diego Zoo in San Diego, CA, October 30, 2012. Jaguars are the largest cats in the Western Hemisphere and the third largest of the world’s cats. REUTERS/San Diego Zoo/Handout (UNITED STATES - Tags: ANIMALS ENVIRONMENT ANNIVERSARY) NO SALES. NO ARCHIVES. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY.

In this publicity photograph taken and released October 30, 2012, by the San Diego Zoo, Tatqiq, an 11-year-old female polar bear at the zoo, attempts to drown a Halloween lawn ornament in the shape of a Frankenstein monster. REUTERS/Tammy Spratt/San Diego Zoo/Copyright Zoological Society of San Diego/Handout (UNITED STATES - Tags: ANIMALS ENVIRONMENT) NO SALES. NO ARCHIVES. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY.

Almaz, a 3-year-old male white African lion, plays with a pumpkin inside his enclosure during the Zoo Halloween Weekend event at the Royev Ruchey Zoo in Russia’s Siberian city of Krasnoyarsk, October 26, 2012. Zoo employees held a competition for the best Halloween pumpkin, after which the pumpkins were presented to the animals.

Aurora, a 2-year-old female polar bear, plays with a pumpkin inside her open air cage during the Zoo Halloween Weekend event at the Royev Ruchey Zoo in Russia’s Siberian city of Krasnoyarsk, October 26, 2012. Zoo employees held a competition for the best Halloween pumpkin, after which the pumpkins were presented to the animals.